Yeah I think we should try to fix this. libvirt could avoid issuing 'info balloon' if it knows the VM is paused, but that has a built-in race condition if QEMU pauses the guest on I/O error or watchdog. Only QEMU can avoid the race - it should simply skip the extended statistics update if the CPUs are paused, and return the most recent previously obtained info instead.

In bug 626544 there is a similar problem to this one, except that it occurs when the guest OS itself is crashed, rather than paused by QEMU. Upstream Anthony suggested that we need some kind of timeout instead of waiting forever for the guest to respond.

Technical note added. If any revisions are required, please edit the "Technical Notes" field
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New Contents:
Due to issues caused when query-balloon hangs when unable to get the stat from a guest this functionality has been temporarily disabled.

Technical note updated. If any revisions are required, please edit the "Technical Notes" field
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Diffed Contents:
@@ -1 +1 @@
-Due to issues caused when query-balloon hangs when unable to get the stat from a guest this functionality has been temporarily disabled.+Due to issues caused when query-balloon hangs when it's unable to get the stats from a guest, this functionality has been temporarily disabled.

According to comment 15 and comment 16, this bug has been fixed, will change status to verified.
For RHEL guest, virtio ballooning can do evict and enlarge memory.
For windows guest, ballooning does not work totally, we already have bug 610787 report balloon issues, and will clarify and keep tracking this new windows issue on bug 610787.

Event posted on 09-08-2010 08:22am EDT by Glen Johnson
------- Comment From santwana.samantray@in.ibm.com 2010-09-08 08:19
EDT-------
Hello Redhat,
I verified this issue in RHEL6 Snap13 release(k.v-2.6.32-70.el6.x86_64),
and this seems to be fixed. Suspend/resume of the KVM guests is happening
fine using virsh. We can close this issue now.
Thanks,
Santwana
This event sent from IssueTracker by jkachuck
issue 1283623

Red Hat Enterprise Linux 6.0 is now available and should resolve
the problem described in this bug report. This report is therefore being closed
with a resolution of CURRENTRELEASE. You may reopen this bug report if the
solution does not work for you.